Switching regulator is a vitally important devices. Switching regulators are building blocks used extensively in power systems, industry, motor, communication, networks, digital systems, consumer electronics, computers, and any other fields that high efficient voltage regulating functions.
Switching regulators (i.e., DC-TO-DC converters) can provide output voltages which can be less than, greater than, or of opposite polarity to the input voltage. Prior Art FIG. 1 illustrates a basic architecture of a conventional switching regulator 100. The conventional switching regulator 100 basically consists of an oscillator, a reference circuit, an error amplifier, a modulator including a comparator, resistors, and a control logic circuit. Control technique of switching regulators has typically used two modulators: a pulse-width modulator and a pulse-frequency modulator. The output dc level is sensed through the feedback loop including two resistors. An error amplifier compares this sampled output voltage and the reference voltage. The output of the error amplifier is compared against a periodic ramp generated by the saw tooth oscillator. The pulse-width modulator output passes through the control logic to the high voltage power switch. The feedback system regulates the current transfer to maintain a constant voltage within the load limits. In other words, it insures that the output voltage comes into regulation. However, it takes a long time until the output reaches the equilibrium after the system starts. Since a power supply of a core processor is connected to one of the outputs of switching regulators in most system applications, even the core processor should stand by until it receives the regulated output from the switching regulator, too. Therefore, unfortunately, the conventional switching regulator 100 of Prior Art FIG. 1 can not be efficiently implemented in integrated circuit (IC), system-on-chip (SOC), monolithic circuit, and discrete circuit since power and time are wasted until the output voltage of the switching regulator comes into regulation. In most switching regulator applications, it is highly desirable to start switching regulators to start immediately for higher power efficiency. In addition, the conventional switching regulator 100 has taken a long time to be simulated and verified before they are fabricated. The simulation time in designing the conventional switching regulator 100 is absolutely proportional to time to require the output voltage of the switching regulators to be regulated. Hence, this long simulation time adds additional cost and serious bottleneck to design time-to-market. In other words, the slow start-up of the switching regulator increases simulation time.
Thus, what is finally needed for a cost-effective switching regulator that can provide zero start-up time to increase power efficiency, reduce power and time consumption until the output voltage of switching regulators comes into regulation, and reduce significantly design time for better time-to-market. The present invention satisfies these needs by providing four embodiments utilizing a small number of transistors.